INVESTIGATION OF SOIL TREATMENT SYSTEMS FOR SEPTIC TANK EFFLUENT. I. DESIGN, FUNCTION, HYDRAULIC PROPERTIES, INPUT AND OUTPUT
The design, function, hydraulic properties, input and output of eight sand filter systems and eight infiltration systems were investigated. The designed hydraulic loads were in some cases high and ranged from 28-100 L m-2d-l for the infiltration sites and from 30-130 L m-2d-1 for the sand filters. Older sites had clay pipes with open connections and newer ones had PVC-pipes with holes or transverse cuts. Seven of the sites were designed for intermittent operation. Both infiltration soils and filter sands were in accordance with the guidelines. Three sites were improperly constructed and six sites did not have any remarks at all. Sewer infiltration of ground water or stormwater was clearly present in four of the sites. Corrosion of concrete due to H2S was present in almost all sites. The removal of suspended solids in the septic tanks was found acceptable with an effluent mean concentration of 158 mg/1. “Complete abstract not presented.”